This project seeks to define methods and mechanisms for controlling osteogenesis by means of inductively-coupled-pulsing electromagnetic fields, established external to the organism. Both in vivo studies of fracture healing in a rat femoral osteotomy model and in vitro studies of collagen synthesis and Ca45 release by osteogenic cells are used. Primary emphasis is focused on elaborating those pulse characteristics, e.g. shape, width, amplitude and repetition rates, which have biologic significance during bone formation and repair. Attempts are made to correlate the rate and amount of Ca45 release by pre-labeled cells with increases in collagen synthesis by osteogenic cells and with increases in fracture healing, as measured radiographically, histologically and by mechanical testing. BIBLIOGRAPHIC REFERENCES: Bassett, C.A.L. and Pawluk, R.J. Noninvasive Methods for Stimulating Osteogenesis, J. Biomed. Mater. Res. 9, 371-374, 1975. Tornberg, D.N., Basett, C.A.L. and Rice, R.W. Protein Polysaccharide Activation of the Resting Periosteum: A Light and Electron Microscopic Study, JBJS 57-A: 577, 1975. (Abstract).